Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 210834
SWOD48
SPC AC 210833

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0333 AM CDT MON APR 21 2014

VALID 241200Z - 291200Z

...DISCUSSION...
SEVERAL POTENTIALLY SIGNIFICANT CONVECTIVE EVENTS ARE POSSIBLE
DURING THE DAY4-8 TIME PERIOD.  UNFORTUNATELY...GFS AND ECMWF DIFFER
CONSIDERABLY IN THEIR EVOLUTION OF THREE MAJOR SYNOPTIC-SCALE
COMPONENTS.  THE FIRST BEING THE AMPLITUDE OF UPPER LOW OVER THE
GREAT LAKES...2...SWD EXTENT OF SFC FRONT OVER THE PLAINS/MS
VALLEY...AND 3...AMPLITUDE OF SHORT WAVE/UPPER LOW OVER THE SWRN
U.S.

WHILE STRONG CONVECTION MAY ULTIMATELY LINGER INTO THE DAY4 PERIOD
AHEAD OF PROGRESSIVE COLD FRONT ACROSS THE MID MS VALLEY...LIMITED
MOISTURE/BUOYANCY SHOULD PREVENT SIGNIFICANT ORGANIZED SEVERE TSTM
ACTIVITY ACROSS THIS REGION.  OF MORE CONCERN IS THE 00Z/144-HR
ECMWF FORECAST WHICH SHARPENS A DRYLINE ACROSS KS...SWD INTO NWRN
TX.  STRONG MID-LEVEL FLOW IS FORECAST TO OVERSPREAD THIS BOUNDARY
ACROSS A BROAD...MOIST AND POTENTIALLY VERY UNSTABLE AIR MASS.
CLASSIC SEVERE EVENT COULD UNFOLD ACROSS THIS REGION SATURDAY WITH
SIGNIFICANT SEVERE POSSIBLE DOWNSTREAM ACROSS THE ERN PORTIONS OF
THE SRN PLAINS/MS VALLEY SUNDAY...AND LOWER MS VALLEY/CNTRL GULF
STATES DAY8.

HOWEVER...GFS IS CONSIDERABLY MORE AMPLIFIED WITH THE UPPER LOW OVER
THE GREAT LAKES AND BLOCKING HIGH OVER CNTRL CANADA FORCING A
DOMINANT SFC ANTICYCLONE SWD ACROSS THE MIDDLE OF THE CONUS.  SFC
FRONT PLUNGES INTO NORTH TX BY SATURDAY AFTERNOON AND EFFECTIVELY
UNDERCUTS STRONGER SWLY FLOW ALOFT AHEAD OF SWRN UPPER LOW.  THIS
SCENARIO WOULD SUGGEST A NARROW WEDGE OF HIGHER INSTABILITY WITHIN
UPSLOPE REGION OF NM COULD SUPPORT MEANINGFUL SEVERE.  WHILE SEVERE
TSTMS WOULD BE POSSIBLE SOUTH OF POLAR FRONT...FRONTAL POSITION
RAISES UNCERTAINTY REGARDING PLACEMENT OF MOST ORGANIZED SEVERE
THREAT.  FOR THIS REASON PREDICTABILITY IS TOO LOW TO WARRANT AN
OUTLOOK THIS PERIOD.

..DARROW.. 04/21/2014



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